The disclosed invention is directed toward an improved construction for a reinforcing fabric for belts. More specifically, the disclosed reinforcing fabric is a composite fabric which provides the belt with superior properties such as high rip resistance, transverse tear resistance, impact resistance, anti-fraying, and flexibility.
Current conveyor belts are constructed with multiple fabric plies. The belt designs utilize plies of all straight warp or solid woven designs or polyester and nylon multi-ply fabrics. Such singular fabric constructions limit the obtainable physical properties of the belt.
The Morrison patents, U.S. Pat. No. 4,371,580, 4,518,647, all disclose multiple fabric plies within agricultural belting material. The outer fabric plies have less resistance to stretching and a greater flex fatigue life than the inner fabric plies.
Conveyor belting with composite fabric plies are also known in the art.
U.S. Pat. No. 5,495,935 discloses conveyor belting with a multi-layer fabric. The fabric is formed of two woven scrims, with an intermediate elastomeric layer. The woven scrims are connected by a plurality of entangled staple fibers.
U.S. Pat. No. 4,813,533 discloses a conveyor belting formed of two woven layers and an intermediate non-woven mat interconnected by a binder yarn. Prior to being joined, the layers are saturated with a polymeric resin. The resin fills all the voids in each textile fabric layer. One exemplary belting described is suitable for a working tensile load of 200 pounds per inch width, and the composite ply has a thickness of about 0.200 inch, with an overall belt thickness of about 0.700 inch.
U.S. Pat. No. 4,928,812 discloses a PVC conveyor belting with a multi-layer fabric designed for heavy load applications. The reinforcing layer is a composite of three layers, with upper and lower woven fabrics of cotton warp and nylon weft yarns, and an intermediate layer of alternating aramid and cotton load bearing cables with a diameter of 4 to 15 mm. The alternating aramid and cotton load bearing cables are spaced a distance of 0.5 to 2 times the cable diameter. The three layers are connected to each other by pairs of nylon binder yarns.
Conventional straight warp fabric designs are also associated with problems such as fabric stringing and lack of flexibility. Such problems are eliminated by the disclosed invention.
The present invention is directed toward a belting with at least one layer of reinforcing fabric of the inventive structure. The inventive fabric is defined by a composite structure wherein all of the layers of the fabric substantively contribute to the overall strength of the fabric. Due to the contribution of each layer of the composite fabric, the fabric has, high rip resistance, transverse tear resistance, impact resistance, anti-fraying, and flexibility than other known and conventional reinforcing belt fabrics. The inventive fabric may be employed as the sole reinforcing structure in a belt or combined with other layers for multiple ply beltings. The number of plies and the combinations employed are dependent upon the desired application for the belting.
In accordance with the present invention, a reinforcing fabric for a belting is disclosed. The reinforcing fabric is a composite fabric which provides the belt with superior properties such as high rip resistance, transverse tear resistance, impact resistance, anti-fraying, and flexibility.
In accordance with the present invention, the composite has two woven layers and an intermediate third layer of straight warp yarns. Each layer of the fabric, the two woven layers and the third layer, contributes approximately 25-40% to the overall strength of the fabric.
In accordance with a further aspect of the present invention, each layer of the composite fabric contributes substantially equally to the overall strength of the fabric.
In accordance with a further aspect of the present invention, the two woven layers and the intermediate third layer of the composite fabric are bound together by a binder yarns extending from a first woven layer, through the intermediate third layer, to the second woven layer.
In a further aspect of the present invention, the 10 to 75% of the weft yarns of the first and second woven layers may be monofilament cords, thereby increasing the traverse properties of the fabric and the belt formed with the composite fabric.
In one embodiment of the disclosed invention, the belting is reinforced solely with the composite fabric. The composite fabric formed with the selective replacement of the monofilment cords are particularly useful for the single ply belting. The belting is also provided with rubber skim layers on each side of the reinforcing ply. Such beltings are particularly useful for light duty belting and conveyor applications.
In another embodiment of the disclosed invention, a multiple ply belting is disclosed. The composite fabric is the central reinforcing ply, with outer fabric plies and intermediate rubber skim layers. When the composite fabric is combined with other types of reinforcing fabric plies, the composite fabric provides approximately 50 to 75% of the overall belting strength. Multiple composite plies may be used in such multiple ply belting. Such beltings are particularly useful for heavy-duty belting and conveyor applications.
Definitions
xe2x80x9cBinder Yarnxe2x80x9d denotes yarn that is used to bind together different yarns in a fabric.
xe2x80x9cFabricxe2x80x9d denotes a network of essentially unidirectionally extending cords/yarns, which may be twisted, and which may in turn be composed of a plurality of a multiplicity of filaments (which may also be twisted). The fabric is woven and flexible.
xe2x80x9cFilament Yarnxe2x80x9d denotes yarn that is formed of continuous and equal length strands.
xe2x80x9cSpun Yarnxe2x80x9d denotes yarn that is formed of a plurality of stands of unequal lengths twisted together to form a yarn.
xe2x80x9cMonofilament Yarnxe2x80x9d denotes a yarn that is a single continuous strand.
xe2x80x9cWarpxe2x80x9d refers to a network of essentially unidirectional extending cords/yarns, which extend in the longitudinal direction of the belt.
xe2x80x9cWeftxe2x80x9d (filling) refers to the cord/yarn placed at right angles to the warp cords/yarns.
xe2x80x9cWoven Fabricxe2x80x9d refers to the interlacing of two sets of yarn, the warp and weft yarns, at right angles.
xe2x80x9cPlain Weavexe2x80x9d refers to a type of weave wherein each warp yarn interlaces one yarn at a time with each weft yarn and vise versa. Plain weave fabric has the same appearance on both sides of the fabric.
xe2x80x9cTwill Weavexe2x80x9d refers to a type of weave wherein there are fewer interlacings between the warp and weft yarns than plain weave fabrics. Twill weaves are characterized by diagonal lines on the fabric.
xe2x80x9cYarnxe2x80x9d: a generic term for a continuous strand of textile fibers or filaments. Yarn occurs in the following forms:
1) a number of fibers twisted together,
2) a number of filaments laid together without twist;
3) a number of filaments laid together with a degree of twist;
4) a single filament with or without twist (monofilament).